There are a wide variety of known apparatus for measuring the torque transmitted by a rotating member, such as a rotating shaft. Often, torque is measured as a function of relative rotation between an input component and an output component such as coaxial drive shafts connected by an elastic coupling which allows for relative rotation in response to applied torque.
Many such devices use a pair of concentric disks respectively mounted on the relatively rotatable shafts and which rotate relative to one another according to the torsional angular deflection of the shafts. The disks are provided with aperture means in the form of slots, teeth or the like through which light is transmitted from a light source located on one side of the rotating disks to a light pickup located on the opposite side of the rotating disks.
The problem with torque measuring apparatus of the character described above is that complicated electronics often are used and are not appropriate for high speed systems. For example, U.S. Pat. No. 2,586,540 to Holden, dated Feb. 19, 1952, utilizes a summing of pulses from multiple slots. It can be understood that such summing approaches are very difficult to adapt to high speed applications. Another, more recent example is shown in U.S. Pat. No. 4,446,746 to Aoshima et al, dated May 8, 1984, wherein the counting of discrete light transmitting slits are used in relatively rotatable disks. These and other prior approaches to measuring torque also encounter resolution problems with the transmitted light when operating at high speeds.
This invention is directed to solving the problems identified above by providing a very simple torque measuring apparatus which relies simply on the depiction of light intensity wherein a continuously variable signal is produced throughout its operating range in direct proportion to the applied torque.